TORONTO, Oct 2 (Reuters) - Canada's main stock index ended lower in a volatile session on Thursday as weakness in the price of Brent crude oil weighed on energy shares and a drop in copper prices hit mining companies. The Toronto Stock Exchange's S&P/TSX composite index unofficially closed down 44.80 points, or 0.3 percent, at 14,760.64. Six of the 10 main sectors on the index closed in the red. (Reporting by John Tilak, editing by G Crosse)